The Finger Board operates the 68HC11 in "Special Mode". This causes the interrupt vectors to be located at address $BFC0-BFFF. While operating in "Special Mode", the 68HC11 can switch back and forth between expanded mode operation and single-chip mode. Interactive C switches the 68HC11 to single-chip mode when it communicates with the LCD since the LCD module cannot communicate at the normal rate of the peripheral bus.

On power-up with S1 depressed, the 68HC11 enters "Special Bootstrap Mode". This is when the internal boot loader is used to upload a more extensive bootloader which will then load your srecord program code. After your program code has been loaded and a reset is issued, the 68HC11 enters "Special Test Mode" and will automatically jump to the program with the reset vector location stored at $BFFE:BFFF.

When using other languages, make sure to declare your interrupt vectors in the "Special Mode" range of $BFC0 to $BFFF.

The Finger Board II now has the option to set the reset vector to location $FFFE:FFFF with jumper JP18 (MODB).

For more information, please see chapter 3 of the Motorola 68HC11 reference manual.

How much free memory do I have after loading the IC pcode?
After loading the pcode, there are approximately 16320 bytes of available program space. The pcode source code can be modified and re-compiled to take up a smaller footprint in memory. Routines such as the IR and Motor PWM subroutines can be deleted if not needed for your application.

This is the approximate breakdown of the memory space. (Thanks to fredm@media.mit.edu)

LCD

The Finger Board uses LCD's with the Hitachi chip set HD44100 and HD44780. Some of the older LCD displays require a -5volt bias and will not work. If the version of the LCD contains a single row header, 1 X 14, connect the pins in the same pattern as on JP2. Pin 1 on LCD connects to pin 1 on JP2 etc.